The state Department of Environmental Protection is joining conservation groups in objecting to plans to conduct seismic testing of ocean sediments off Barnegat Bay.

The proposal, approved by the National Marine Services earlier this week, will be challenged in federal court by the Christie administration, according to a letter from DEP Commissioner Bob Martin. The challenge will be filed today, according to the DEP.

The issue is a contentious one, with conservationists interested in protecting the Jersey Shore’s coastal resources saying the blasting will adversely impact marine life, including dolphins and whales.

To protest the decision, conservationists gathered at Barnegat Light last night to mobilize support against the proposal. “The fight is not over,’’ said Cindy Zipf, executive director of Clean Ocean Action.

Other environmentalists praised the state for trying to block the blasting.

“We’re glad the Christie administration is going to court to block seismic testing of our coast,’’ said Jeff Tittel, director of the New Jersey Sierra Club. “Seismic testing will not only hurt marine mammals, impact our fisheries, and could open us for offshore drilling. We believe the public is on our side and so is the law.’’

Rutgers University, the University of Texas, and the National Science Foundation will conduct the study. It will use massive air guns to study sea sediment to assess climate change and sea level rise. The testing will take place about 15 miles off Barnegat Inlet.

The DEP has opposed the timing of the seismic testing program, saying it would negatively impact marine fisheries, species migration patterns, and breeding of commercial fishes.

“We remain hopeful that, at the very best, this initiative will be rescheduled for a less impactful time of year,’’ DEP Commissioner Bob Martin said in the letter to a conservation group, announcing its intent to challenge the federal action.